AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI+SC-FrM

Paper MI+SC-FrM9
Electrical Spin Injection from a Ferromagnetic Metal Into a Semiconductor: Schottky vs Al@sub 2@O@sub 3@ Tunnel Barriers

Friday, November 7, 2003, 11:00 am, Room 316

Session: Semiconductor Spin Injection
Presenter: O.M.J. van 't Erve, Naval Research Laboratory
Authors: O.M.J. van 't Erve, Naval Research Laboratory
A.T. Hanbicki, Naval Research Laboratory
C.H. Li, Naval Research Laboratory
G. Kioseoglou, Naval Research Laboratory
B.T. Jonker, Naval Research Laboratory
G. Itskos, SUNY Buffalo
R. Mallory, SUNY Buffalo
M. Yasar, SUNY Buffalo
A. Petrou, SUNY Buffalo
Correspondent: Click to Email
Efficient injection of spin-polarized electrons from a metal into a semiconductor requires a high resistance interface contact such as a tunnel barrier.@footnote 1@ The natural Schottky tunnel barrier which forms at the Fe/AlGaAs interface provides highly efficient spin injection, and a polarization of more than 32% has been measured in a GaAs quantum well detector.@footnote 2@ The pseudo-triangular shape and high interface doping level of the Schottky tunnel contact are factors which are quite different from those encountered for the canonical rectangular barrier typically formed from Al@sub 2@O@sub 3@. It is therefore of interest to compare the characteristics and performance of an Al@sub 2@O@sub 3@ tunnel barrier with the Fe/AlGaAs Schottky barrier in essentially identical MBE-grown device structures. The Al@sub 2@O@sub 3@ barrier is formed on top of an AlGaAs/GaAs spin-polarized light-emitting diode (spin-LED) by multi-step in situ natural oxidation of thin evaporated Al layers. A ferromagnetic metal layer is evaporated on top of this tunnel barrier and provides the spin-polarization of the injected electrons. We measure the spectral features, intensities and polarization of the electroluminescence from the surface emitting spin-LEDs, and compare these directly with similar data for the Fe Schottky contact and with literature to obtain insight into various aspects of the spin injection process. @FootnoteText@ This work was supported by the DARPA SpinS program, ONR, and NSF. @footnote 1@ E. I. Rashba, Phys. Rev. B 62, R16267 (2000).@footnote 2@ A.T. Hanbicki et al, Appl. Phys. Lett. 82 (9 June 2003).